% https://github.com/cmhughes/latexindent.pl/issues/24
\begin{lem}
	\label{1.19:lem1}
	\[ \left\{
		\begin{matrix}
			p \in \al \\
			q \notin \al
		\end{matrix}
		\right\}\implies p < q.\]
\end{lem}
